It is known from U.S. Pat. No. 7,364,391 to produce bevel gears by providing a multi-axis free form gear cutting machine and a single disk cutter. The single disk cutter is positioned relative to the workpiece so that it cuts the first part of the gap. The tool and the workpiece are then re-positioned so that the remaining part of the gap is cut. Initially, a first transformation is made from the machine axes settings of the first cutter of the conventional machine to the co-ordinates of the theoretical cradle type basic machine. These basic settings are then transformed to the multi-axis machine settings and the first part of a gap is cut. Next a series of transformations is made similarly in order to cut the remaining portion of the gap. This method could be used also for grinding, because it converts machining with two interlocking tools to machining with a single tool.
It is known from Ochduszko K.: Koa zbate, Tom 2. Wykonanie i montaż. WNT, Warszawa, 1976, which is a book on gear technology, to manufacture gear teeth by using profile and generating methods. In case of profile methods the tooth profile results from the tool profile. In case of generating methods the tooth profile is generated, being created as an envelope of consecutive positions of the tool profile. Here, besides the cutting motion of the tool, a roll motion is carried out (the generating motion). The generating motion consists of a rotary motion of the workpiece and a transverse motion.
It is known in the industry (source: Ochduszko K.: Koa zbate, Tom 2. Wykonanie i montaż. WNT, Warszawa, 1976) to machine gear teeth by using generating methods and disk tools. There are appropriate tools available, for green machining (e.g. disk milling cutters) as well as for finishing machining (e.g. disk grinding wheels). There are also machine tools available, which provide appropriate work motions made by the tool relative to the workpiece, resulting in machining of the workpiece. Among the generating methods that allow for cutting of correct bottom land shape, MAAG, NILES and KOLB methods are known.
Prior art methods for generating of gear teeth with disk tools did not utilize the synchronization between the lengthwise motion and the roll motion, which caused the total work travel of the machine, required for complete generating of the tooth flank, to be relatively long. In case of the American U.S. Pat. No. 7,364,391, discussed earlier, the lengthwise travel is zero and the tool is positioned in the middle of the teeth width, which causes the bottom land to reflect the shape of the tool and therefore it is concave curved, which is detrimental to gear's strength.
The inconvenience of the prior art methods for generating of the gear teeth with correct bottom land shape using disk tools is that at least one component motion of the work motion is oscillatory, and therefore it is carried out many times at each gap being machined, which is required in order to completely generate the flank surface, and so it takes consequently relatively big amount of time, reducing productivity of those methods.